View source for Varicode

'''Varicode''' is a [[self-synchronizing code]] for use in [[PSK31]]. It supports all [[ASCII]] characters, but the characters used most frequently in English have shorter codes. The space between characters is indicated by a 00 sequence, an implementation of [[Fibonacci coding]].  Originally created for speeding up real-time keyboard-to-keyboard exchanges over low [[Bandwidth (computing)|bandwidth]] links, Varicode is freely available.<ref>{{cite web |author=Steven L Karty, N5SK |title=PSK31 Spec |publisher=ARRL Website |url=http://www.arrl.org/psk31-spec |accessdate=18 Dec 2010}}</ref><ref>{{cite web |title=PSK31: A New Radio-Teletype Mode |author=Peter Martinez, G3PLX |url=http://www.arrl.org/files/file/Technology/tis/info/pdf/x9907003.pdf |accessdate=28 Sep 2017}}</ref><ref>{{cite web |author=ITU Working Party 5A |title=ITU-R M.2034: Telegraphic Alphabet for Data Communication by Phase Shift Keying at 31 Baud in the Amateur and Amateur-Satellite Services. |publisher=International Telecommunication Union (approved Feb, 2013) |url=http://www.itu.int/rec/R-REC-M.5B22-0-201302-D/en |accessdate=21 Feb 2013}}</ref>
==Limitations==
* Varicode provides somewhat weaker compression in languages other than English that use same characters as in English.
==Varicode table==
===Control characters===
{| class="wikitable" style="text-align: center"
|-
! Varicode !! Oct !! Dec !! Hex !! Abbr !! Description
|-
|1010101011 || 000 || 0 || 00 || NUL || [[Null character]]
|-
|1011011011 || 001 || 1 || 01 || SOH || Start of Header
|-
|1011101101 || 002 || 2 || 02 || STX || Start of Text
|-
|1101110111 || 003 || 3 || 03 || ETX || End of Text
|-
|1011101011 || 004 || 4 || 04 || EOT || [[End-of-transmission character|End of Transmission]]
|-
|1101011111 || 005 || 5 || 05 || ENQ ||  Enquiry
|-
|1011101111 || 006 || 6 || 06 || ACK || [[Acknowledge character|Acknowledgment]]
|-
|1011111101 || 007 || 7 || 07 || BEL || [[Bell character|Bell]]
|-
|1011111111 || 010 || 8 || 08 || BS || [[Backspace]]
|-
|11101111 || 011 || 9 || 09 || HT || [[Tab key|Horizontal Tab]]
|-
|11101 || 012 || 10 || 0A || LF || [[Line feed]]
|-
|1101101111 || 013 || 11 || 0B || VT || Vertical Tab
|-
|1011011101 || 014 || 12 || 0C || FF || [[Form feed]]
|-
|11111 || 015 || 13 || 0D || CR || [[Carriage return]]
|-
|1101110101 || 016 || 14 || 0E || SO || [[Shift Out and Shift In characters|Shift Out]]
|-
|1110101011 || 017 || 15 || 0F || SI || [[Shift Out and Shift In characters|Shift In]]
|-
|1011110111 || 020 || 16 || 10 || DLE || Data Link Escape
|-
|1011110101 || 021 || 17 || 11 || DC1 || Device Control 1 (XON)
|-
|1110101101 || 022 || 18 || 12 || DC2 || Device Control 2
|-
|1110101111 || 023 || 19 || 13 || DC3 || Device Control 3 (XOFF)
|-
|1101011011 || 024 || 20 || 14 || DC4 || Device Control 4
|-
|1101101011 || 025 || 21 || 15 || NAK || [[Negative-acknowledge character|Negative Acknowledgement]]
|-
|1101101101 || 026 || 22 || 16 || SYN || Synchronous Idle
|-
|1101010111 || 027 || 23 || 17 || ETB || End of Trans. Block
|-
|1101111011 || 030 || 24 || 18 || CAN || [[Cancel character|Cancel]]
|-
|1101111101 || 031 || 25 || 19 || EM || End of Medium
|-
|1110110111 || 032 || 26 || 1A || SUB || [[Substitute character|Substitute]]
|-
|1101010101 || 033 || 27 || 1B || ESC || [[Escape character|Escape]]
|-
|1101011101 || 034 || 28 || 1C || FS || File Separator
|-
|1110111011 || 035 || 29 || 1D || GS || Group Separator
|-
|1011111011 || 036 || 30 || 1E || RS || Record Separator
|-
|1101111111 || 037 || 31 || 1F || US || Unit Separator
|-
|1110110101 || 177 || 127 || 7F || DEL || Delete
|}
===Printable characters===
{|
|- valign="top"
|
{| class="wikitable" style="text-align: center"
|-
!Varicode !! [[Octal|Oct]] !! [[Decimal|Dec]] !! [[Hexadecimal|Hex]] !! Glyph
|-
|1 || 040 || 32 || 20 || [[Space (punctuation)|SP]]
|-
|111111111 || 041 || 33 || 21 || [[Exclamation mark|!]]
|-
|101011111 || 042 || 34 || 22 || [[Quotation mark|"]]
|-
|111110101 || 043 || 35 || 23 || [[Number sign|#]]
|-
|111011011 || 044 || 36 || 24 || [[Dollar sign|$]]
|-
|1011010101 || 045 || 37 || 25 || [[Percent sign|%]]
|-
|1010111011 || 046 || 38 || 26 || [[Ampersand|&]]
|-
|101111111 || 047 || 39 || 27 || [[Apostrophe (punctuation)|']]
|-
|11111011 || 050 || 40 || 28 || [[Bracket|(]]
|-
|11110111 || 051 || 41 || 29 || [[Bracket|)]]
|-
|101101111 || 052 || 42 || 2A || [[Asterisk|*]]
|-
|111011111 || 053 || 43 || 2B || [[Plus sign|+]]
|-
|1110101 || 054 || 44 || 2C || [[Comma (punctuation)|,]]
|-
|110101 || 055 || 45 || 2D || [[Hyphen|-]]
|-
|1010111 || 056 || 46 || 2E || [[Full stop|.]]
|-
|110101111 || 057 || 47 || 2F || [[Slash (punctuation)|/]]
|-
|10110111 || 060 || 48 || 30 || [[0 (number)|0]]
|-
|10111101 || 061 || 49 || 31 || [[1 (number)|1]]
|-
|11101101 || 062 || 50 || 32 || [[2 (number)|2]]
|-
|11111111 || 063 || 51 || 33 || [[3 (number)|3]]
|-
|101110111 || 064 || 52 || 34 || [[4 (number)|4]]
|-
|101011011 || 065 || 53 || 35 || [[5 (number)|5]]
|-
|101101011 || 066 || 54 || 36 || [[6 (number)|6]]
|-
|110101101 || 067 || 55 || 37 || [[7 (number)|7]]
|-
|110101011 || 070 || 56 || 38 || [[8 (number)|8]]
|-
|110110111 || 071 || 57 || 39 || [[9 (number)|9]]
|-
|11110101 || 072 || 58 || 3A || [[Colon (punctuation)|:]]
|-
|110111101 || 073 || 59 || 3B || [[Semicolon|;]]
|-
|111101101 || 074 || 60 || 3C || [[Less-than sign|<]]
|-
|1010101 || 075 || 61 || 3D || [[Equals sign|=]]
|-
|111010111 || 076 || 62 || 3E || [[Greater-than sign|>]]
|-
|1010101111 || 077 || 63 || 3F || [[Question mark|?]]
|}
|&nbsp;
|
{| class="wikitable" style="text-align: center"
|- valign="bottom"
!Varicode !! [[Octal|Oct]] !! [[Decimal|Dec]] !! [[Hexadecimal|Hex]] !! Glyph
|-
|1010111101 || 100 || 64 || 40 || [[@]]
|-
|1111101 || 101 || 65 || 41 || [[A]]
|-
|11101011 || 102 || 66 || 42 || [[B]]
|-
|10101101 || 103 || 67 || 43 || [[C]]
|-
|10110101 || 104 || 68 || 44 || [[D]]
|-
|1110111 || 105 || 69 || 45 || [[E]]
|-
|11011011 || 106 || 70 || 46 || [[F]]
|-
|11111101 || 107 || 71 || 47 || [[G]]
|-
|101010101 || 110 || 72 || 48 || [[H]]
|-
|1111111 || 111 || 73 || 49 || [[I]]
|-
|111111101 || 112 || 74 || 4A || [[J]]
|-
|101111101 || 113 || 75 || 4B || [[K]]
|-
|11010111 || 114 || 76 || 4C || [[L]]
|-
|10111011 || 115 || 77 || 4D || [[M]]
|-
|11011101 || 116 || 78 || 4E || [[N]]
|-
|10101011 || 117 || 79 || 4F || [[O]]
|-
|11010101 || 120 || 80 || 50 || [[P]]
|-
|111011101 || 121 || 81 || 51 || [[Q]]
|-
|10101111 || 122 || 82 || 52 || [[R]]
|-
|1101111 || 123 || 83 || 53 || [[S]]
|-
|1101101 || 124 || 84 || 54 || [[T]]
|-
|101010111 || 125 || 85 || 55 || [[U]]
|-
|110110101 || 126 || 86 || 56 || [[V]]
|-
|101011101 || 127 || 87 || 57 || [[W]]
|-
|101110101 || 130 || 88 || 58 || [[X]]
|-
|101111011 || 131 || 89 || 59 || [[Y]]
|-
|1010101101 || 132 || 90 || 5A || [[Z]]
|-
|111110111 || 133 || 91 || 5B || [[Bracket|<nowiki>[</nowiki>]]
|-
|111101111 || 134 || 92 || 5C || [[Backslash|\]]
|-
|111111011 || 135 || 93 || 5D || [[Bracket|<nowiki>]</nowiki>]]
|-
|1010111111 || 136 || 94 || 5E || [[Caret|^]]
|-
|101101101 || 137 || 95 || 5F || [[Underscore|_]]
|}
|&nbsp;
|
{| class="wikitable" style="text-align: center"
|- valign="bottom"
!Varicode !! [[Octal|Oct]] !! [[Decimal|Dec]] !! [[Hexadecimal|Hex]] !! Glyph
|-
|1011011111 || 140 || 96 || 60 || [[Grave accent|']]
|-
|1011 || 141 || 97 || 61 || [[a]]
|-
|1011111 || 142 || 98 || 62 || [[b]]
|-
|101111 || 143 || 99 || 63 || [[c]]
|-
|101101 || 144 || 100 || 64 || [[d]]
|-
|11 || 145 || 101 || 65 || [[e]]
|-
|111101 || 146 || 102 || 66 || [[f]]
|-
|1011011 || 147 || 103 || 67 || [[g]]
|-
|101011 || 150 || 104 || 68 || [[h]]
|-
|1101 || 151 || 105 || 69 || [[i]]
|-
|111101011 || 152 || 106 || 6A || [[j]]
|-
|10111111 || 153 || 107 || 6B || [[k]]
|-
|11011 || 154 || 108 || 6C || [[l]]
|-
|111011 || 155 || 109 || 6D || [[m]]
|-
|1111 || 156 || 110 || 6E || [[n]]
|-
|111 || 157 || 111 || 6F || [[o]]
|-
|111111 || 160 || 112 || 70 || [[p]]
|-
|110111111 || 161 || 113 || 71 || [[q]]
|-
|10101 || 162 || 114 || 72 || [[r]]
|-
|10111 || 163 || 115 || 73 || [[s]]
|-
|101 || 164 || 116 || 74 || [[t]]
|-
|110111 || 165 || 117 || 75 || [[u]]
|-
|1111011 || 166 || 118 || 76 || [[v]]
|-
|1101011 || 167 || 119 || 77 || [[w]]
|-
|11011111 || 170 || 120 || 78 || [[x]]
|-
|1011101 || 171 || 121 || 79 || [[y]]
|-
|111010101 || 172 || 122 || 7A || [[z]]
|-
|1010110111 || 173 || 123 || 7B || [[Bracket|{]]
|-
|110111011 || 174 || 124 || 7C || [[Vertical bar|{{pipe}}]]
|-
|1010110101 || 175 || 125 || 7D || [[Bracket|}]]
|-
|1011010111 || 176 || 126 || 7E || [[Tilde|~]]
|}
|}
===Character lengths===
Beginning with the single-bit code "1", valid varicode values may be formed by prefixing a "1" or "10" to a shorter code.  Thus, the number of codes of length ''n'' is equal to the [[Fibonacci number]] ''F<sub>n</sub>''.  Varicode uses the 88 values of lengths up to 9 bits, and 40 of the 55 codes of length 10.
As transmitted, the codes are two bits longer due to the trailing delimiter 00.
{| class="wikitable"
|+ASCII characters by varicode length
! Bits || Codes || Characters
|-
| 1 || 1 || SP
|-
| 2 || 1 || e
|-
| 3 || 2 || o t
|-
| 4 || 3 || a i n
|-
| 5 || 5 || LF CR l r s
|-
| 6 || 8 || - c d f h m p u
|-
| 7 || 13 ||, . = A E I S T b g v w y
|-
| 8 || 21 || HT ( ) 0 1 2 3 : B C D F G L M N O P R k x
|-
| 9 || 34 || ! " # $ ' * + / 4 5 6 7 8 9 ; &lt; &gt; H J K Q U V W X Y [ \ ] _ j q z {{pipe}}
|-
| 10 || 40 || NUL SOH STX ETX EOT ENQ ACK BEL BS VT FF SO SI DLE DC1 DC2 DC3 DC4 NAK SYN ETB CAN EOM SUB ESC FS GS RS US % & ?  @ Z ^ ` { } ~ DEL
|}
==References==
{{Reflist}}
{{Compression methods}}
[[Category:Character encoding]]